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Reuse getDecimalCodeRepresentation from SAS instead of duplicating code

This commit is contained in:
Hugh Nimmo-Smith 2022-10-18 12:23:21 +01:00
parent 0acbd9c531
commit 811d6d87ae
2 changed files with 30 additions and 41 deletions
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17
matrix-sdk-android/src/main/java/org/matrix/android/sdk/api/rendezvous/channels/ECDHRendezvousChannel.kt
View File

@ -29,7 +29,7 @@ import org.matrix.android.sdk.api.rendezvous.RendezvousTransport
import org.matrix.android.sdk.api.rendezvous.model.RendezvousError
import org.matrix.android.sdk.api.rendezvous.model.SecureRendezvousChannelAlgorithm
import org.matrix.android.sdk.api.util.MatrixJsonParser
import org.matrix.android.sdk.internal.extensions.toUnsignedInt
import org.matrix.android.sdk.internal.crypto.verification.SASDefaultVerificationTransaction
import org.matrix.olm.OlmSAS
import timber.log.Timber
import java.security.SecureRandom
@ -48,20 +48,9 @@ class ECDHRendezvousChannel(override var transport: RendezvousTransport, theirPu
private const val KEY_SPEC = "AES"
private val TAG = LoggerTag(ECDHRendezvousChannel::class.java.simpleName, LoggerTag.RENDEZVOUS).value
// n.b. we are only aver processing byte array that we have generated, so we can make assumptions about the length
// this is the same representation as for SAS but we delimit by dashes instead of spaces for readability
private fun getDecimalCodeRepresentation(byteArray: ByteArray): String {
val b0 = byteArray[0].toUnsignedInt() // need unsigned byte
val b1 = byteArray[1].toUnsignedInt() // need unsigned byte
val b2 = byteArray[2].toUnsignedInt() // need unsigned byte
val b3 = byteArray[3].toUnsignedInt() // need unsigned byte
val b4 = byteArray[4].toUnsignedInt() // need unsigned byte
// (B0 << 5 | B1 >> 3) + 1000
val first = (b0.shl(5) or b1.shr(3)) + 1000
// ((B1 & 0x7) << 10 | B2 << 2 | B3 >> 6) + 1000
val second = ((b1 and 0x7).shl(10) or b2.shl(2) or b3.shr(6)) + 1000
// ((B3 & 0x3f) << 7 | B4 >> 1) + 1000
val third = ((b3 and 0x3f).shl(7) or b4.shr(1)) + 1000
return "$first-$second-$third"
return SASDefaultVerificationTransaction.getDecimalCodeRepresentation(byteArray).replace(" ", "-")
}
}

54
matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/verification/SASDefaultVerificationTransaction.kt
View File

@ -82,6 +82,33 @@ internal abstract class SASDefaultVerificationTransaction(
// older devices have limited support of emoji but SDK offers images for the 64 verification emojis
// so always send that we support EMOJI
val KNOWN_SHORT_CODES = listOf(SasMode.EMOJI, SasMode.DECIMAL)
/**
* decimal: generate five bytes by using HKDF.
* Take the first 13 bits and convert it to a decimal number (which will be a number between 0 and 8191 inclusive),
* and add 1000 (resulting in a number between 1000 and 9191 inclusive).
* Do the same with the second 13 bits, and the third 13 bits, giving three 4-digit numbers.
* In other words, if the five bytes are B0, B1, B2, B3, and B4, then the first number is (B0 << 5 | B1 >> 3) + 1000,
* the second number is ((B1 & 0x7) << 10 | B2 << 2 | B3 >> 6) + 1000, and the third number is ((B3 & 0x3f) << 7 | B4 >> 1) + 1000.
* (This method of converting 13 bits at a time is used to avoid requiring 32-bit clients to do big-number arithmetic,
* and adding 1000 to the number avoids having clients to worry about properly zero-padding the number when displaying to the user.)
* The three 4-digit numbers are displayed to the user either with dashes (or another appropriate separator) separating the three numbers,
* or with the three numbers on separate lines.
*/
fun getDecimalCodeRepresentation(byteArray: ByteArray): String {
val b0 = byteArray[0].toUnsignedInt() // need unsigned byte
val b1 = byteArray[1].toUnsignedInt() // need unsigned byte
val b2 = byteArray[2].toUnsignedInt() // need unsigned byte
val b3 = byteArray[3].toUnsignedInt() // need unsigned byte
val b4 = byteArray[4].toUnsignedInt() // need unsigned byte
// (B0 << 5 | B1 >> 3) + 1000
val first = (b0.shl(5) or b1.shr(3)) + 1000
// ((B1 & 0x7) << 10 | B2 << 2 | B3 >> 6) + 1000
val second = ((b1 and 0x7).shl(10) or b2.shl(2) or b3.shr(6)) + 1000
// ((B3 & 0x3f) << 7 | B4 >> 1) + 1000
val third = ((b3 and 0x3f).shl(7) or b4.shr(1)) + 1000
return "$first $second $third"
}
}
override var state: VerificationTxState = VerificationTxState.None
@ -371,33 +398,6 @@ internal abstract class SASDefaultVerificationTransaction(
return getDecimalCodeRepresentation(shortCodeBytes!!)
}
/**
* decimal: generate five bytes by using HKDF.
* Take the first 13 bits and convert it to a decimal number (which will be a number between 0 and 8191 inclusive),
* and add 1000 (resulting in a number between 1000 and 9191 inclusive).
* Do the same with the second 13 bits, and the third 13 bits, giving three 4-digit numbers.
* In other words, if the five bytes are B0, B1, B2, B3, and B4, then the first number is (B0 << 5 | B1 >> 3) + 1000,
* the second number is ((B1 & 0x7) << 10 | B2 << 2 | B3 >> 6) + 1000, and the third number is ((B3 & 0x3f) << 7 | B4 >> 1) + 1000.
* (This method of converting 13 bits at a time is used to avoid requiring 32-bit clients to do big-number arithmetic,
* and adding 1000 to the number avoids having clients to worry about properly zero-padding the number when displaying to the user.)
* The three 4-digit numbers are displayed to the user either with dashes (or another appropriate separator) separating the three numbers,
* or with the three numbers on separate lines.
*/
fun getDecimalCodeRepresentation(byteArray: ByteArray): String {
val b0 = byteArray[0].toUnsignedInt() // need unsigned byte
val b1 = byteArray[1].toUnsignedInt() // need unsigned byte
val b2 = byteArray[2].toUnsignedInt() // need unsigned byte
val b3 = byteArray[3].toUnsignedInt() // need unsigned byte
val b4 = byteArray[4].toUnsignedInt() // need unsigned byte
// (B0 << 5 | B1 >> 3) + 1000
val first = (b0.shl(5) or b1.shr(3)) + 1000
// ((B1 & 0x7) << 10 | B2 << 2 | B3 >> 6) + 1000
val second = ((b1 and 0x7).shl(10) or b2.shl(2) or b3.shr(6)) + 1000
// ((B3 & 0x3f) << 7 | B4 >> 1) + 1000
val third = ((b3 and 0x3f).shl(7) or b4.shr(1)) + 1000
return "$first $second $third"
}
override fun getEmojiCodeRepresentation(): List<EmojiRepresentation> {
return getEmojiCodeRepresentation(shortCodeBytes!!)
}